I never compared RL and Disco Pirates, but only the princible civilian companies work with.
Now, even those traders you mentioned had those guns to defend themselves when attacked, not to actively hunt down pirates.
Anyway, my opineo still stands, OSC shouldn't go actively after slavers, there is to little gained by this. They are free however, to pay freelancer and mercenary companies companies to do it. Doing it themselves would make little to no sense.